This invention relates to a display for a record/playback device and, more particularly, to such a display which unambiguously indicates the number of the particular message that has been reached on a bi-directionally movable record medium.
The invention disclosed herein is usable with and is an improvement of the invention described in copending application Ser. No. 564,480, filed Dec. 21, 1983, U.S. Pat. No. 4,688,117 and assigned to the assignee of the present invention. As described therein, record/playback devices, such as dictation and/or transcription machines, provide indications of messages, such as letters, that have been recorded. Typically, a predetermined signal, such as a special tone signal, referred to generally as a "cue" tone, is recorded under the control of the machine user at the completion of each message or letter which he dictates. Such cue tones are utilized during transcription to control the energization of a light element display to apprise the transcriptionist of the relative locations and lengths of the respective messages, or letters, that have been dictated. Examples of light element displays of the aforementioned type are described generally in U.S. Pat. Nos. 4,051,540, 4,200,893 and 4,378,577.
In addition to, or in place of, these light element displays, a numerical display may be provided to indicate the number of the particular message which has been dictated or which now is in position to be played back, as during transcription or during a review of previously dictated messages. One type of message-number display is described in copending application Ser. No. 564,480. There, when an end-of-message cue signal, referred to herein as a letter cue signal, is recorded, numerical information representing the number of messages that had been recorded up until then is updated. This numerical information is selectively accessed and displayed, thus indicating to the user the number of messages, or letters, which had been recorded previously. Thus, if the user has just completed recording message number 3, and has signified the end of that message by recording a letter cue signal, the display will indicate "3" when the message number information is accessed. As the user then records his fourth message, further access of the message number information will, nevertheless, result in the display "3". Of course, this numerical information is updated once the next (i.e. the fourth) letter cue signal is recorded.
As also described in the aforementioned copending application, cue signals representing the location of dictated instructions also may be recorded on the record medium. These cue signals are referred to as instruction cue signals; and the numerical display may be selectively controlled to indicate to the user the number of instructions which have been recorded. Thus, the display control arrangement is provided with means for storing numerical information representing the number of messages that have been recorded as well as means for storing numerical information representing the number of instructions that have been recorded. Each type of numerical information may be selectively accessed and displayed.
In the display described in the aforementioned application, a position counter is incremented and decremented as the record medium (which, typically, is a magnetic tape) moves in the forward and reverse directions, respectively. Cooperating with the record medium transport apparatus is a pulse generator which supplies pulses to a counter that provides a position count representing the position of the record medium relative to a reference location. As an example, if the record medium is a magnetic tape bi-directionally driven between supply and take-up reels, a so-called chopper wheel mechanically coupled to the supply reel generates pulses at a rate corresponding to the rotary speed of that supply reel. Hence, the position count is obtained simply by counting the chopper pulses. When a letter cue signal is recorded, the count then present in the position counter is stored at an addressed location in a memory; and each address is used as the aforementioned numerical information representing the number of the message that had just been recorded. When the tape is rewound, for example, the position counter is decremented; and when the position count is decremented to a count equal to a stored end-of-message count, the address at which that end-of-message count is stored is utilized to display the number of the letter which has been reached.
Similarly, when an instruction cue signal is recorded, the count of the position counter is stored as an instruction count at an addressed memory location, and the address of that location is used to display the number of the instruction which has been recorded. When the tape is moved to a position at which the instruction cue signal is recorded, the address at which the instruction count is stored is used to display the number of the instruction which has been reached.
It had been thought preferable to reset the aforementioned position counter each time a fresh record medium (e.g. a fresh tape cassette) is loaded into the dictation/transcription machine. By resetting the position counter, the position count then will be incremented from a reference [0000] count as the record medium advances for the purpose of dictation. Such resetting of the position count to [0000] presents no problem if the tape included in the freshly loaded cassette is fully rewound. That is, if the reference location of the newly-loaded tape corresponds to the very beginning thereof, the position counter merely will increment from its [0000] count and, since the tape cannot be rewound further, the counter cannot be decremented below its [0000] count.
However, ambiguity is introduced into the aforementioned message number display if the fresh cassette that is loaded into the dictation/transcription machine initially is positioned at some arbitrary reference location. That is, if the tape therein is not fully rewound, the resetting of the position counter to [0000] does not represent the beginning of the tape. The user may dictate one or more messages on the newly-loaded tape, resulting in the storage of end-of-message counts and the provision of numerical information representing the number of each recorded message, as in the manner mentioned above and as more fully disclosed in the aforementioned patent application. As the tape is reversed, the position counter is decremented; and when the position count becomes equal to a stored end-of-message count, the address at which that end-of-message count is stored is used to display the number of the letter that has been reached. It is possible, however, that the user may rewind the tape beyond the arbitrary reference location thereof, that is, beyond the starting point at which dictation commenced. The position counter then will be decremented below its [0000] count which, as is typical, results in a "roll over" of the count to a maximum value, such as [9999]. Further reversal of the tape results in further decementing of the position count from [9999] towards a lower value.
A technique that can be used for displaying the number of the message that has been reached on the tape is based upon a comparison of the position count to the stored end-of-message counts. If the position count is greater than one stored end-of-message count but is less than another, the number of the message which has been reached, that is, the number of the message then juxtaposed the record/playback transducer of the dictation/transcription machine, is the number associated with the larger end-of-message count (i.e. the number of the message is equal to, or derived from, the address at which the larger end-of-message count is stored). Alternatively, the number of the message which is displayed may be equal to the number that is associated with the smaller stored end-of-message counts plus one (i.e. the displayed message number is equal to 1 plus the address of the location at which the smaller end-of-message count is stored).
An example of the aforementioned technique for determining the number of the message which has been reached is best understood from a numerical example. Let it be assumed that the tape included in a newly-loaded cassette has not been fully rewound but, nevertheless, the position count is reset to [0000]. Let it be further assumed that a first letter cue signal is recorded at a location corresponding to a position count of [950], a second letter cue signal is recorded at a location corresponding to a count of [1140], and the user presently is in the process of dictating a third message. The position count will be greater than [1140] and, consequently, the message number display, when accessed, will indicate to the user that the tape presently is at a location corresponding to letter "3". This is because the position count is greater than the last-stored end-of-message count [1140], and this stored end-of-message count is associated with letter "2". Now, if the tape is rewound such that the position count is decremented to a count less than [1140] but greater than a count of [950], the message number display will indicate that the tape has reached letter "2". With further reverse movement of the tape, the position count continues to decrement; and when this count becomes less than [950], the message number "1" is displayed, indicating that the first message which had been dictated on the tape has been reached and is juxtaposed the record/playback transducer. Now, if the tape is further rewound to a location which precedes the reference location, that is, if the tape is rewound beyond its starting point, the position count is decremented below [0000] and "rolls over" to a count of [9999]. This count is greater than the largest stored end-of-message count [1140] and, thus, the message number which is displayed is message number "3". Thus, the user is erroneously apprised that the third message (which he had been in the process of dictating) has been reached.
The foregoing explains the ambiguity which may occur when the position count normally is reset to a zero count [0000] when a cassette is replaced, and the new cassette has not been fully rewound prior to resetting the position count. This ambiguity may erroneously indicate to the user that a particular message recorded on the tape has been reached when, in fact, the tape actually is nowhere near that message.